Quantum Chemical Approach Research Articles

Putative Identification of 47 Compounds from Jieyu Anshen Granule and Proposal of Pharmacopeia Quality-Assessment Strategy Using TCM-Specific Library with UHPLC-Q-Exactive-Orbitrap-MS.

Jieyu Anshen Granule is a traditional Chinese medicine prescription used for depression and primarily comprises five herbal medicines: Zhizi, Chaihu, Zhigancao, Danggui, and Yuanzhi. This study established a traditional Chinese herbal medicine-specific library using emerging ultra-high-performance liquid chromatography-quadrupole-orbitrap-tandem mass spectrometry analysis. Through library comparison, the study has fulfilled isomers distinction. As a result, 47 compounds were simultaneously and putatively identified from Jieyu Anshen Granule, including 12 unexpected compounds and 35 expected compounds. The unexpected compounds comprised cyclocommunol, 5-hydroxyflavone, tangeretin, 3,5,6,7,8,3',4'-heptemethoxyflavone, calycosin-7-O-β-D-glucoside, 7,4'-dihydroxyflavone, naringenin-7-O-β-D-glucoside, matrine, betaine, jervine, alantolactone, and hypericin. Among the 35 expected compounds, saikosaponin A, saikosaponin D, glycyrrhizic acid, geniposide, ligustilide, and polygalaxanthone III were further investigated using a quantum chemistry approach. Based on these, an effective quality assessment strategy is proposed for the Pharmacopeia, involving the simultaneous analysis of glycyrrhizic acid, geniposide, ligustilide, polygalaxanthone III, saikosaponins A and D through ultra-high-performance liquid chromatography-quadrupole-orbitrap-tandem mass spectrometry analysis. This strategy enables the detection of adulteration in relation to Zhizi, Chaihu, Zhigancao, Danggui, and Yuanzhi in Jieyu Anshen Granule. The findings of unexpected compounds will deepen the understanding of chemistry in Jieyu Anshen Granule.

Capturing Dichotomic Solvent Behavior in Solute-Solvent Reactions with Neural Network Potentials.

Simulations of chemical reactivity in condensed phase systems represent an ongoing challenge in computational chemistry, where traditional quantum chemical approaches typically struggle with both the size of the system and the potential complexity of the reaction. Here, we introduce a workflow aimed at efficiently training neural network potentials (NNPs) to explore energy barriers in solution at the hybrid density functional theory level. The computational burden associated with training at the PBE0-D3(BJ) level is bypassed through the use of active and transfer learning techniques, whereas extensive sampling of the transition state region is accelerated by well-tempered metadynamics simulations using multiple time step integration. These NNPs serve to explore a puzzling solute-solvent reactivity route involving the ring opening of N-enoxyphthalimide experimentally observed in methanol but not in 2,2,2-trifluoroethanol (TFE). This reaction represents a challenging example characterized by intricate hydrogen bonding networks and structurally ambiguous solvent-sensitive transition states. The methodology successfully delivers detailed free energy surfaces and relative energy barriers in agreement with experiment. These barriers are associated with an ensemble of transition states involving the direct participation of up to five solvent molecules. While this picture contrasts with the single transition state structure assumed by current static models, no drastic qualitative difference is observed between the formed hydrogen bonding networks and the number of participating solvent molecules in methanol or TFE. The dichotomy between the two solvents thus essentially arises from an electronic effect (i.e., distinct nucleophilicity) and from the larger conformational entropy contributions in methanol. This example underscores the critical role that dynamic simulations at the ab initio levels play in capturing the full complexity of solute-solvent interactions.

QUANTUM-CHEMICAL AND AGROCHEMICAL INVESTIGATIONS OF Cu++ METAL COMPLEX BASED ON HYDROXYBENZOIC ACIDS

The crystal arrangement of molecules is necessary to determine what kind of supramolecular structures (2- or 3-dimensional framework) are formed as a result of intermolecular interactions, furthermore, it depends on the physicochemical properties of the crystal, for example, melting temperature, solubility, stability, activity and etc.. However, such qualitative analysis can be replaced by quantitative analyzes based on quantum-chemical approaches. One of them is based on the calculation of a surface with the same electron charge density, called the Hirshfeld surface. In our case, the main contribution of intermolecular interactions of mixed-ligand metal complex [Cu(PHBA)2(MEA)2] by Hirshfeld surface analysis and quantum chemical DFT calculations has shown that that they correspond to strong H‧‧‧O/O‧‧‧H bonds. Using DFT calculations, it was calculated that an odd electron MO (doublet state) arises when a complex is formed due to an odd d (d9) orbital in the Cu2+ ion of the compound [Cu(PHBA)2(MEA)2]. By the molecular docking studies the investigated complex compound [Cu(PHBA)2](MEA)2] recorded stronger binding energies than auxins taken as a control. The compound [Cu(PHBA)2](MEA)2], which showed the strongest performance, had a result 6% higher than the highest performing natural auxin. Quant-chemical calculation results are tested by agrochemical investigations on the mungbean plant

Insight into crystal structure of 2-methylquinolin-1-ium 2-carboxy-3-nitrobenzoate salt: Hirshfeld surface analysis, quantum chemical approach, and anti-bacterial activity

Insight into crystal structure of 2-methylquinolin-1-ium 2-carboxy-3-nitrobenzoate salt: Hirshfeld surface analysis, quantum chemical approach, and anti-bacterial activity

Mechanisms for the Spin-State Switching of Strapped Ni-Porphyrin Complexes Deposited on Metal Surfaces: Insights from Quantum Chemical Calculations.

The incorporation of molecular switches on nanodevices requires both the intactness of the molecule once deposited on a substrate and the persistence of the reversible switching feature. Recently, the reversible spin-switching of strapped Ni(II)-porphyrin complexes deposited on Ag(111) surface is demonstrated with low-temperature scanning tunneling microscopy (STM). The spin transition is accompanied by the coordination change of the metal center, a phenomenon denominated in coordination-induced spin-state switching (CISSS). In this contribution, the spin switching of the deposited strapped Ni-porphyrin molecules using different quantum chemistry approaches is explored. This calculations inform about the geometry and electronic structure of the adsorbed molecules and the origin of the voltage-dependent switching promoted by the STM tip. Two different mechanisms are inspected to elucidate the key role of the tip, mainly the electron injection between the tip and the molecule and the differential stabilization of the two spin states by the applied electric field between the tip and the silver surface. This study puts in evidence the relevance of the pyridine ligand contained in the strap in the transport properties as in the CISSS process itself.

Determination the Anticorrosive Properties of Trimebutine Maleate for Aluminum Corrosion in 2M HCl Gravimetric and Quantum Chemistry Approaches

The present work evaluated the inhibition properties of (R,S)-2-(dimethylamino)-2-phenylbutyl 3,4,5-trimethoxybenzoate or trimebutine maleate (TM) in aluminum corrosion in 2M hydrochloric acid. Tests were carried out using gravimetric methods and density functional theory (DFT). The results indicate that trimebutine maleate is a good inhibitor of aluminum corrosion in 2M hydrochloric acid at low temperatures. Indeed, the inhibition efficiency of this molecule increases with increasing concentration and decreases with increasing temperature. For an inhibitor concentration of 5.2mM and at 298K, we obtained an inhibition efficiency of 93.61%. The adsorption process is spontaneous, exothermic and follows the Langmuir model. The activation parameters were calculated and analyzed. DFT at the B3LYP/6-311G (d.p) level was used to determine molecular parameters such as EHOMO, ELUMO, ΔE, η, S, μ , A, I, χ, ΔN, ω. These theoretical parameters showed that TM is highly reactive and can both donate and receive electrons from aluminum. They thus confirmed the good inhibition performance of the molecule studied. These parameters were used to explain the inhibition efficiencies obtained. Local selectivity was analyzed using Fukui functions and the dual descriptor to determine possible nucleophilic and electrophilic attack sites.

Improving Optoelectronic Properties of Acceptor–Donor–Acceptor‐Type Non‐Fullerene Acceptors Containing Extended Fused Ring Donor Units for Efficient Organic Semiconductors

Developing efficient small molecule‐based non‐fullerene acceptors (NFAs) has gained huge attention in fabricating high‐efficiency and stable organic solar cells (OSCs). Herein, we designed and characterized eight new NFAs for OSCs. To investigate the potential of these newly designed NFAs series (IBH1–IBH8) for OSCs, various advanced quantum chemical simulation approaches are used and compared with the synthetic reference molecule IBH–R. Due to the extended donor cores, the IBH1–IBH8 molecules possess strong intramolecular and intermolecular interactions, which helps improve the thin‐film surface crystallinity. Moreover, the designed IBH1–IBH8 molecules present improved UV–visible absorption, narrower bandgaps, lower excitation, and binding energies, and improved photovoltaic characteristics. Furthermore, the impact on the intrinsic properties such as transition density matrix, density of state, electrostatic potential, distribution of frontier molecular orbitals, and reorganizational energies of holes and electrons are estimated. Additionally, the charge‐transfer phenomenon by establishing a donor:acceptor blend (PTB7–Th:IBH4) is analyzed, their geometric analyses are studied, and a good charge‐shifting process is found at the donor:acceptor interface. With these results, we demonstrated the enhancements in the optoelectronic and photovoltaic characteristics of OSCs by performing a simple end‐capped modulation. Hence, these molecules are recommended for the development of efficient and cost‐effective OSCs.

Reduced Cost Computation and Exploitation of Accurate Radial Interaction Potentials for Barrier-Less Processes.

Barrier-less steps are typical of radical and ionic reactions in the gas-phase, which often take place in extreme environments such as the combustion reactors operating at very high temperatures or the interstellar medium, characterized by ultralow temperatures and pressures. The difficulty of experimental studies in conditions mimicking these environments suggests that computational approaches can provide a valuable support. In this connection, the most advanced treatments of these processes in the framework of transition state theory are able to deliver accurate kinetic parameters provided that the underlying potential energy surface is sufficiently accurate. Since this requires a balanced treatment of static and dynamic correlation (which play different roles in different regions), very sophisticated and expensive quantum chemical approaches are required. One effective solution of this problem is offered by the computation of accurate one-dimensional radial potentials, which are then used to correct the results of a Monte Carlo sampling performed by cheaper quantum chemical approaches. In this paper, we will show that, for a large panel of different barrier-less reaction steps, the radial potential is ruled by the R-4 term and that addition of a further R-6 contribution provides quantitative agreement with the reference points. The consequences of this outcome are not trivial, since the reference potential can be fitted by a very limited number of points possibly with a nonlinear spacing. In the case of reaction steps ruled by long-range transition states, generalized expressions are also given for computing reaction rates in the framework of the phase-space theory. All these improvements pave the way toward the computation of reaction rates for barrier-less reactions involving large molecules.

Exploring the electronic properties of doped zirconia for enhanced optoelectronic applications: A quantum chemical approach

Zirconia (ZrO2) is a versatile material with applications in various fields due to its exceptional mechanical strength, thermal stability, and chemical resistance. In recent years, interest has surged in utilizing doped ZrO2 as photocatalysts. This study investigates the electronic properties of ZrO2 upon doping with non-metal elements sulfur (S), selenium (Se), and tellurium (Te) using first-principle calculations. The effects of different doping concentrations on the band structure and density of states (DOS) have been examined. Calculations using GGA show significant reductions in the band gap upon doping, indicating potential for improved optoelectronic performance. Specifically, using accurate DFT + U approach we found that doping ZrO2 with 25 % S led to a band gap reduction from 5.4 eV to 1.2 eV, demonstrating promising result for photovoltaic applications. This study provides valuable insights into the electronic properties of doped ZrO2 (ZrO2-xQx, Q = S, Se and Te, x = 0.25, 0.5 and 2) paving the way for tailored applications in various technological domains.

Elucidating the Advancement in the Optoelectronics Characteristics of Benzoselenadiazole-Based A2-D-A1-D-A2-Type Nonfullerene Acceptors for Efficient Organic Solar Cells.

The potential applications of nonfullerene acceptors (NFAs) such as tunable band gaps, improved charge separation, wide-range absorption, enhanced power conversion efficiency, and operational stability make them highly favorable for organic photovoltaic applications. Herein, we designed eight novel structurally modified nonfused benzoselenadiazole (BSe)-based A2-D-A1-D-A2-type NFAs for efficient organic solar cells (OSCs). These newly modeled BSe-based NFA series contain BSe as the central core. We employed strong electron-withdrawing moieties at terminal acceptor A2 to further enhance the optical, optoelectronics, and photovoltaic characteristics of OSCs. These designed molecules (HNM1-HNM8) along with the synthetic reference molecule (HNM) were thoroughly characterized by using efficient and advanced quantum chemical simulation approaches. Thus, to ascertain the enhancement of both optical and photochemical response, a thorough density functional theory (DFT) study was carried out using the M062X level in association with the 6-31G(d,p) basis set. All of the investigated molecules (HNM1-HNM8) had their excited states calculated using the time-dependent density functional theory method. The newly designed molecules (HNM1-HNM8) presented narrower band gaps, improved absorption and optoelectronics properties, and reduced excitation and binding energies. The electrostatic potential, density of states, transition density matrix, ionization potential, and electron affinity analysis of this newly designed (HNM1-HNM8) series revealed a strong coherence with those of the reference HNM molecule. Electron density difference mapping allowed us to visualize the spatial movement of electrons between the donor and acceptor molecules during excitation. This insight helps us to understand the efficiency of charge separation and recombination processes that are critical for the performance of organic photovoltaics. The reorganization energy and charge transfer analysis suggests that HNM1-HNM8 molecules could act as NFAs for organic photovoltaic applications to enhance their efficiency further. The donor: acceptor charge transfer analysis was also carried out, which revealed that the PTB7-Th:HNM2 donor:acceptor complex shows a great charge transportation process at the donor-acceptor interface. Moreover, the photovoltaic analysis shows that the designed (HNM1-HNM8) NFA series has a great potential to produce improved open-circuit voltage and fill factor values, which may be helpful in enhancing the overall PCEs of the OSCs.

Unravelling the structure and reactivity of N,O-heterocycles: a multifaceted quantum chemical approach using a benzoxazole derivative as a case study

Unravelling the structure and reactivity of N,O-heterocycles: a multifaceted quantum chemical approach using a benzoxazole derivative as a case study

Investigation on induced smectic phases in double hydrogen bond liquid crystal complexes derived from aromatic carboxylic acids: Experimental and quantum chemical approaches

In the present study, double Hydrogen bond liquid crystal (HBLC) complexes in different mole ratio (1:1 and 1:2) have been isolated from symmetrical aromatic dicarboxylic acid of non-mesogenic compound 1,3-Phenylenediacetic acid (1,3-PDA) and mesogenic compound 4-n-dodecyloxybenzoic acid (12 OBA). Fourier transform infrared Spectroscopy (FTIR) explores the presence of functional groups in the title complexes. Formation of H-bond between 1,3-PDA and 12 OBA is experimentally confirmed by observing the FTIR peak at 3639 cm−1 (1:1 ratio). Induced mesophases and its textures along with transition temperatures are analyzed using polarizing optical microscope (POM) and differential scanning calorimetry (DSC). The layered structures (smectic phases) and their molecular mechanism has been analyzed using density functional theory (DFT). Further, the establishment of H-bond in the title complex has been investigated with the aid of optimized geomentry, molecular electrostatic potential (MEP) and reduced density gradient (RDG) analysis. The band gap energy of title complex (1:1) is calculated by UV–Vis spectrometer and the same has been justified by HOMO-LUMO studies. Maximum absorption in the UV region and moderate bandgap energy (Eg = 4.22 eV) of the title complex clearly indicates its potential application in NLO, optoelectronics and laser tuning devices. In addition to that, LC parameters and its effect on mesophase are reported using experimental and computational methods.

Enhancing perovskite solar cells performance through tailored design: pyridine-functionalized phenothiazine derivatives with modified end-capped acceptor moieties

Abstract Future energy resources are being developed using clean and renewable energies since these sources offer environmentally friendly and sustainable choices to traditional sources like fossil fuels. Among various renewable energy sources, solar energy is becoming increasingly efficient with advancements in organic photovoltaic systems. Organic semiconductor materials, which require high electron affinity and possess desirable optical and electronic properties, are crucial for these systems. Researchers are constantly trying to increase the role of photovoltaic materials in optoelectronic applications. With current energy demands, there is a shift from traditional solar cells to perovskite photovoltaic materials due to their significant contributions to renewable energy. Therefore, we have designed a new stream of donor- π -acceptor (D- π -A) type pyridine functionalized phenothiazine derivates-based donor materials, resulting in nine fabricated HTMs (PT1-PT9), by substituting the terminals with thiophene and acceptors moieties respectively to enhance the photovoltaic properties of perovskite solar cells (PSCs). All newly proposed materials were computationally examined to estimate their optoelectronics, geometrical, and photovoltaic properties using quantum chemical approach, and then compared to the reference. For organic hole-transporting materials, a heterocyclic phenothiazine core (PTZ) has been proven effective as it has feasible structure modifications, excellent electron-donating properties, and straightforward synthesis. The study of electronic parameters (density of state, frontier molecular orbitals, and electrostatic potential ESP), optical properties (light harvesting efficiency, absorption maxima, dipole moment, and first excitation energies) and charge transfer characteristics (electron–hole overlap, transition density matrix) of designed materials revealed that there is an increase in absorption range under the influence of terminal acceptor groups, with lowering the bandgap values compared to the reference. A density of state (DOS) graph and HOMO–LUMO schema are evidence of the electron-withdrawing effect of acceptor moieties. Transition density matrix (TDM) analysis proves reliable charger transfer in designed molecules. Reorganization energy values for designed molecules are lower than the reference making charge transfer carriers more efficient. Additionally, solvation-free energy values (−17.28 to −33.19 Kcalmol−1) and higher dipole moments suggest better surface-wetting and solubility properties. In general, the fabricated materials have exceptional charge mobilities with higher absorption and reduced band gap values that make them suitable and stable candidates for photovoltaic devices.

Accurate Geometries of Large Molecules at DFT Cost by Semiexperimental and Coupled Cluster Templating Fragments.

Accurate geometries of small semirigid molecules in the gas phase are available thanks to high-resolution spectroscopy and accurate quantum chemical approaches. These results can be employed for validating cheaper low-level quantum chemical models or correcting the corresponding structures of large molecules. On these grounds, in this work, a large panel of semiexperimental equilibrium structures already available in the literature is used to confirm the average error (1 mÅ for bond lengths and 2 mrad for valence angles) of a version of the Pisa composite schemes (PCS2), which is applicable to molecules containing up to about 20 atoms. Then, the geometries of 30 additional medium-sized systems were optimized at the PCS2 level to cover a more balanced chemical space containing moieties poorly represented in SE compilations. The final database is available on a public domain Web site (https://www.skies-village.it/databases/) and can be employed for correcting structures of larger molecules obtained by hybrid or double-hybrid density functionals in the framework of the templating molecule approach. Several examples show that corrections based on the structures of building blocks taken from this database reduce the error of the B3LYP geometrical parameters of large molecules by nearly an order of magnitude without increasing the computational cost. Furthermore, the results of different density functional theory (DFT) or wave function (e.g., MP2) models can be improved in the same way by simply computing both the whole molecule and suitable building blocks at the chosen level. Then, whenever reference structures of some building blocks containing up to about 20 atoms are not available, they can be purposely optimized at the PCS2 level by employing reasonable computer resources. Therefore, a new DFT-cost tool is now available for the accurate characterization of large molecules by experiment-oriented scientists.

Electronic structure, global reactivity descriptors and nonlinear optical properties of glycine interacted with ZnO, MgO and CaO for bacterial detection

Modern laboratory medicine relies on analytical instruments for bacterial detection, focusing on biosensors and optical sensors for early disease diagnosis and treatment. Thus, Density Functional Theory (DFT) was utilized to study the reactivity of glycine interacted with metal oxides (ZnO, MgO, and CaO) for bacterial detection. Total dipole moment (TDM), frontier molecular orbitals (FMOs), FTIR spectroscopic data, electronic transition states, chemical reactivity descriptors, nonlinear optical (NLO) characteristics, and molecular electrostatic potential (MESP) were all investigated at the B3LYP/6–31G(d, p) level using DFT and Time-Dependent DFT (TD-DFT). The Coulomb-attenuating approach (CAM-B3LYP) was utilized to obtain theoretical electronic absorption spectra with the 6-31G(d, p) basis set to be more accurate than alternative quantum chemical calculation approaches, showing good agreement with the experimental data. The TDM and FMO investigation showed that glycine/CaO model has the highest TDM (10.129Debye) and lowest band gap (1.643 eV). The DFT computed IR and the experimental FTIR are consistent. The calculated UV-vis spectra showed a red shift with an increase in polarity following an increase in the absorption wavelength due to the interaction with ZnO, MgO, and CaO. Among the five solvents of water, methanol, ethanol, DMSO and acetone, the water and DMSO enhances the UV-Vis absorption. Glycine/CaO model showed high linear polarizability (14.629 × 10−24esu) and first hyperpolarizability (23.117 × 10−30esu), indicating its potential for nonlinear optical applications. The results showed that all model molecules, particularly glycine/CaO, contribute significantly to the development of materials with potential NLO features for sensor and optoelectronic applications. Additionally, MESP confirmed the increased electronegativity of the studied structures. Additionally, glycine/ZnO nanocomposite was synthesized and characterized using IR and UV-visible spectroscopy to determine their structural and spectroscopic features. It was discovered that there was good agreement between the DFT computed findings and the related experimental data. The antibacterial activity of glycine/ZnO nanocomposites against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa were studied in terms of concentration and time. The results showed that increasing the concentration of glycine/ZnO nanocomposite significantly enhanced its antibacterial efficacy by lowering optical density. Notably, Pseudomonas aeruginosa exhibited lower susceptibility to the nanocomposite compared to S. aureus, requiring higher concentrations for effective bactericidal action. In summary, this study contributes novel insights into the dual functionality of glycine-metal oxide complexes, with significant implications as optical biosensor for microbial detection.

Quantum Chemical Approaches for Manipulation and Evaluation of Intracage Microelectric Field Strength of Molecular Containers in Y@C64 and Y@C64X4 (X = Cl, F, and H, Y = NH4Cl, H3O-Cl, and 2H2O).

The effect of an oriented external electric field (EEF) on materials has led to the ongoing development, which stimulates us to consider whether intracage microelectric fields (IMEFs) can be used to substitute for the EEF. Focusing on the manipulation and evaluation of the IMEF of asymmetric molecular containers, the host-guest compounds of interesting pineapple-shaped Y@C64X4 (X = vacant, Cl, F, and H; Y = NH4Cl, H3O-Cl, and 2H2O) are theoretically constructed and the strength of the IMEF was evaluated by the intrapotential energy surface analysis by using the point charge (q = +1) scanning method. Interestingly, the left and right halves of each cage are like two IMEFs connected in reverse series. Both the addition of four X atoms and the orientation of the guest can sensitively influence the IMEF's strengths and directions of both half cages and further determine the entire cage's IMEF. Subsequently, the IMEF can sensitively change the binding characteristics and properties of the guest species. Therefore, the manipulation and evaluation of the IMEF can be achievable. This work may provide support for an asymmetric molecular container with an IMEF to manipulate the novel structural and chemical bond characteristics of the guest species.

Optoelectronic Properties of Triply Twisted Möbius Carbon Nanobelt and the Design of Its Isomeric Nanomaterials

The triply twisted Möbius carbon nanobelt (TMCNB) possesses an extremely distinctive geometric and electronic structure and therefore is anticipated to demonstrate outstanding optical properties. In this paper, through integrating quantum chemical calculations and wave function analysis approaches, in-depth studies are conducted on the one-photon absorption (OPA) and two-photon absorption (TPA) characteristics, aromaticity, and circular dichroism of the TMCNB. Inspired by this structure, we further deform it to construct a novel structure, MCNB2, and verify the stability of this structure, thereby confirming its rationality. Since variations in structure will result in dissimilar optical properties, we also undertake theoretical analyses on the absorption properties and circular dichroism of MCNB2. The outcomes of this study offer a significant theoretical foundation for the design and construction of chiral optoelectronic materials.

Optimizing cold-flow properties and oxidation stability of B40 biodiesel blend with turpentine oil and ethanol: Experimental and quantum chemical approach

This study investigates the effectiveness of turpentine oil and ethanol as cold-flow improvers (CFIs), synergizing as antioxidants for ternary B40 biodiesel blend. Utilizing the response surface methodology (RSM), the effects of these CFIs on the ternary blend, including cloud point (CP), cold filter plugging point (CFPP), filter blocking tendency (FBT), precipitation, and oxidation stability, were comprehensively evaluated. The analysis of variance (ANOVA) presented that a linear model best describes the impact of CFIs on CP, whereas quadratic models more accurately represent CFPP, FBT, and oxidation stability. The results also demonstrate that 2FI was identified as the most suitable model for describing precipitation responses. The optimal concentrations of turpentine oil and ethanol were determined to be 10 % v/v and 0.5 % v/v, respectively, resulting in predicted values for CP, CFPP, FBT, precipitation, and oxidation stability of 10.4 °C, 9.0 °C, 1.31, 9.09 mg/100 mL, and 225 minutes, respectively. Theoretical insights from density functional theory (DFT) calculations confirmed that the primary interaction controlling wax formation in biodiesel blends is the strong hydrogen bonding between monostearin and pinene, a major component of turpentine oil, which effectively disrupts wax crystallization. This study presents a novel approach to enhancing B40 biodiesel cold-flow properties and maintaining its oxidation stability by utilizing the synergistic effects of turpentine oil and ethanol to optimize B40 biodiesel formulation.

Effect of Electron-Donating Substituents and an Electric Field on the ΔEST of Selected Imidazopyridine Derivatives: A DFT Study.

A series of thermally activated delayed fluorescent (TADF) molecules having an imidazopyridine acceptor, a benzene linker, and a 9,9-dimethyl-9,10-dihydroacridine donor are designed and examined using a quantum chemical approach. The above framework spatially separates the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), minimizing their overlap, ultimately resulting in a reduced energy gap between the excited singlet and triplet states (ΔEST). The impact of electron-donating substituents (-Me, -Et, -t-Bu, -OMe, and -NMe2) on the donor moiety of the parent molecule 2-(4-(9,9-dimethylacridin-10(9H)-yl)phenyl)imidazo[1,2-a]pyridine-3,6-dicarbonitrile (Ac-CNImPy) is investigated. The calculated results revealed that for a given substituent, the para-substituted derivatives exhibit relatively less ΔEST, compared to that of the respective ortho- and meta derivatives. The value of ΔEST decreased with an increase in the electron-donating capacity of the substituent. Additionally, the ΔEST of the disubstituted derivatives is found to be less than that for the monosubstituted derivatives. The charge transport studies revealed that molecules with strong electron-donating substituents act as electron transporters. The effect of an external electric field (EEF) on ΔEST of the parent molecule Ac-CNIMPY and its derivative is also examined and revealed that the ΔEST can be further reduced by applying an electric field of appropriate strength in a direction perpendicular to the dipole moment of the molecule and in the plane of the acceptor moiety.

Assessing realistic binding energies of some essential interstellar radicals with amorphous solid water. A fully quantum chemical approach

Assessing realistic binding energies of some essential interstellar radicals with amorphous solid water. A fully quantum chemical approach